The future of HIV/AIDS prevention is looking promising, thanks to a new candidate HIV vaccine…
Having overcome technical hurdles that previous vaccine efforts could not, a new HIV vaccine has already proved powerful anti-HIV antibody response in animal tests.
It is based on the HIV envelope protein, Env.
This complex, shape-shifting molecule has been notoriously difficult to produce in vaccines in a way that induces useful immunity to HIV. However, the Scripps Research scientists found a simple, elegant method for stabilising Env proteins in the desired shape even for diverse strains of HIV.
“We see this new approach as a general solution to the long-standing problems of HIV vaccine design,” says principal investigator Jiang Zhu, associate professor in the Department of Integrative Structural and Computation Biology at Scripps Research.
The big idea behind the new vaccine
The idea has been to inoculate people with the whole Env protein or subunits of it to stimulate the production of Env-binding antibodies, in the hope that these antibodies will prevent HIV from infecting host cells in future exposures to the virus.
So far, of course, no HIV vaccine has been effective in large-scale clinical trials. Many researchers believe that an HIV vaccine can work if it presents Env proteins to the immune system in a way that closely resembles the shape of Env on a real virus before it has infected a cell. But presenting Env correctly has been a huge challenge.
Testing the new vaccine
In mice, Zhu and his team found, a sample Env-on-nanoparticles vaccine, within just eight weeks, elicited antibodies that in lab tests successfully neutralised a naturally circulating HIV strain – of a type that prior candidate vaccines generally have failed against.
“This is the first time any candidate HIV vaccine has induced this desired type of antibody response in mice,” Zhu says. Similarly unprecedented results were obtained in rabbits, demonstrating that the nanoparticle-based approach is clearly superior to the use of isolated Env proteins – it elicits a significantly stronger response and does so much more quickly.
Further tests are now underway in 24 monkeys at the National Institutes of Health-sponsored Southwest National Primate Centre in San Antonio, Texas.
“We’re now testing two candidate vaccines based on Env trimers from different HIV strains, plus a third candidate vaccine that is a cocktail of three Env-based vaccines,” says Ji Li, Ufovax CEO. “We think this new approach represents a true breakthrough after 30 years of HIV vaccine research.”
Source: Scripps Research Institute via www.sciencedaily.com
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